Lightning or surge arresters are typically connected to power lines to carry electrical surge currents to ground and, thus, prevent damage to the lines and equipment connected thereto. Arresters offer high resistance to normal voltage across power lines, yet offer very low resistance to surge currents produced by sudden high voltage conditions caused by lightning strikes, for example. After the surge, the voltage should drop and the arrester should then normally return to a high resistance state. However, in the case of arrester malfunction or failure, the high resistance state is not resumed, and the arrester continues to provide an electrical path from the power line to ground. Ultimately, the line will fail due to a short circuit condition or breakdown of the distribution transformers, and the arrester will require replacement.
To avoid line failure, disconnectors are commonly used in conjunction with arresters to separate a malfunctioning arrester from the circuit and provide visual indication of arrester failure. Conventional disconnectors have an explosive charge to destroy the circuit path and physically separate the electrical terminals. Upon exploding, however, some prior disconnectors propelled parts of the device at high velocity into the surrounding area endangering persons and property in the vicinity. In addition, fragile housings, used to ensure disconnection upon detonation, often broke during installation. Other prior disconnectors did not generate enough explosive force to break the circuit.
Examples of prior disconnector devices are disclosed in McMorris U.S. Pat. No. 2,305,436; Hedlund et al U.S. Pat. No. 2,820,869; MacRae U.S. Pat. No. 2,957,967; Hicks U.S. Pat. No. 2,989,608; Robinson U.S. Pat. No. 3,017,539; Riley U.S. Pat. No. 3,100,246; Snell, Jr. U.S. Pat. No. 3,239,631; Carothers et al. U.S. Pat. No. 3,291,937; Carothers U.S. Pat. No. 3,588,773; Irie et al. U.S. Pat. No. 3,668,458; Carothers et al. U.S. Pat. No(s). 3,679,938 and 3,702,419; Cunningham et al. 3,869,650; Stetson U.S. Pat. No. 4,204,238; Barnes U.S. Pat. No. 4,479,105; Sykes et al. U.S. Pat. No. 4,503,414; and Cunningham U.S. Pat. No. 4,738,823.